The container with the cap is structured from a container body and a cap that is attachable and detachable to and from the container body. As the container with a cap, there is one in which the cap can be lightly taken off from the container body with a light operating force by elastic deformation of the elastic ring body. With the container disclosed in Patent literature 1 shown below, the cap forms a part of an exterior of the container and comprises a cap body having a cylindrical peripheral side wall that opens downwards, when the container body is positioned upright, and a ring body fitted inside the cap body.
The cap body has an engaging protrusion projecting inwardly from the lower end thereof. The container body is also provided with an engaging projection at an outer surface thereof. When the cap is pushed in above the container body, the protrusion of the cap body and the projection of the container body come in contact, and when the cap is pushed in further, the cap itself elastically deforms, and goes over the projection of the container body. Thus, the protrusion and projection of both parts engage, and the cap is fitted to the container body.
The ring body is provided with protrusions on the outer surface thereof which project in opposite directions from each other and are exposed to the outside from holes that penetrate from the inside to the outside of the cap body. In a state where the cap is fitted to the container body, the lower end of the ring body comes in contact with the container body, and at least one of the lower end of the ring and a contacting section of the container body with the ring body is made as an inclined surface. For example, the container body has an inclined surface above the engaging projection by gradually reducing in diameter the cylindrical shape of the container body toward the upper end, which becomes an opening of the container body. When the protrusions of the ring body which are exposed to the outer side of the cap body are pressed, the ring body is urged upwardly while coming in contact with the inclined surface. As a result, the cap body rises and the engaging protrusion of the cap body go over the engaging projection of the container body, and the engagement is released. Namely, the cap can be easily taken off.
Further, while ensuring an engaging strength in which the cap and the container do not come off accidentally, the cylindrical cap body has a discal sealing section at a ceiling portion thereof to seal an opening of the container body in order to ensure the sealing performance. As a structure of the sealing section, a tubular plug that is concentric with the disk-like ceiling section is formed by hanging down from the ceiling of the cap body, and an outer diameter of the tubular plug is made to snugly fit to an inner diameter of the opening of the container. Therefore, when the cap is fitted, the outer surface of the tubular plug contacts the inner surface of the opening of the container and seals the container. Note that, in Patent Literature 1, as the sealing section, it has been proposed to construct such that a plate-shaped packing is provided and the lower surface of the packing comes in contact with the opening rim of the container body, or a structure that a protrusion is provided to fit into a central opening of the ceiling section to be adaptable to the case where a middle plug is fitted in a central hole in the opening of the container body.